This was written by Marion Zimmer Bradley when she was younger, as is mentioned in the Wikipedia article.
http://www.timelineuniverse.net/MiddleE ... fArwen.htmBradley took an active role in science-fiction and fantasy fandom, promoting interaction with professional authors and publishers and making several important contributions to the subculture. In 1966, Bradley became a cofounder of the Society for Creative Anachronism, and is credited with coining the name of that group. In the 1970s, as part of the contemporary wave of enthusiasm for J. R. R. Tolkien's fictional world of Middle-earth, she wrote two short fanfic stories about Arwen and published them in chapbook format; one of them, "The Jewel of Arwen", also appeared in her professional anthology The Best of Marion Zimmer Bradley (1985), although it was dropped from later reprints.
I really like this one. I think its well written and captures the characters well, and also does a nice job of matching Tolkien's writing style.
http://www.timelineuniverse.net/MiddleE ... fArwen.htm
This one is a little more ambitious, and I think she pulls it off pretty well, right up until her attempt to explain black breath as radioctive isotopes.